<?php
namespace App\Lib\Payment;

class AlipayEncrypt
{
    /**
     * 加密方法
     * @param string $str
     * @return string
     */
     public static function encrypt($str,$screct_key){
    	//AES, 128 模式加密数据 CBC
    	$screct_key = base64_decode($screct_key);
    	$str = trim($str);
    	$str = self::addPKCS7Padding($str);
    	$iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128,MCRYPT_MODE_CBC),1);
    	$encrypt_str = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $screct_key, $str, MCRYPT_MODE_CBC);
    	return base64_encode($encrypt_str);
    }

    /**
     * 解密方法
     * @param string $str
     * @return string
     */
     public static function decrypt($str,$screct_key){
    	//AES, 128 模式加密数据 CBC
    	$str = base64_decode($str);
    	$screct_key = base64_decode($screct_key);
    	$iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128,MCRYPT_MODE_CBC),1);
    	$encrypt_str = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $screct_key, $str, MCRYPT_MODE_CBC);
    	$encrypt_str = trim($encrypt_str);

    	$encrypt_str = self::stripPKSC7Padding($encrypt_str);
    	return $encrypt_str;

    }

    /**
     * 填充算法
     * @param string $source
     * @return string
     */
    public static function addPKCS7Padding($source){
    	$source = trim($source);
    	$block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);

    	$pad = $block - (strlen($source) % $block);
    	if ($pad <= $block) {
    		$char = chr($pad);
    		$source .= str_repeat($char, $pad);
    	}
    	return $source;
    }
    /**
     * 移去填充算法
     * @param string $source
     * @return string
     */
    public static function stripPKSC7Padding($source){
    	$source = trim($source);
    	$char = substr($source, -1);
    	$num = ord($char);
    	if ($num == 62) {
            return $source;
        }
    	$source = substr($source,0,-$num);
    	return $source;
    }
}
